A lot goes down in the premiere of the new CW series “18 to Life,” the drama adapted from a Canadian hit. In the first scene, eighteen-year-old Tom proposes to Jessie, the girl next door. By the end of the episode, they’re hitched.

I know what you’re thinking: somebody’s knocked up.

But nobody is. And that’s a good thing — right? When a pop-culture tide brought us “Juno” and “Knocked Up,” critics decried the glamorization of out-of-wedlock pregnancy. A show about teens getting married just because they’re in love should make us all feel good. Shouldn’t it?

Watch and decide for yourself — but stick around for episode two before you decide. It’s then that Jessie and Tom settle into married life — and man, do they settle in. She bosses him around. He becomes instantly crotchety.

All of this would be enough to undermine the show’s appeal. But what makes it really hard to watch is Tom and Jessie’s casual discourse on sex. They’re not youth group lifers who tied the knot so they could get it on. We learn that they were sexually active before marriage, and they’ll be sexually active after it. When Jessie confesses to having once slept with another guy, her exasperated excuse is: “It was like, two years ago” — when she was 16. Once settled in their marital home, Tom and Jessie are all over each other. There are many cringe-inducing references to “christening the new place.” Never mind that their “new place” is actually the attic of Tom’s parents’ home.

What is it that makes this so creepy, even though the kids have made it legal? It’s that they’re still kids. And even actors can’t mask the fact that it’s unnatural to watch kids behave like they’re as entitled to sex as they are to silly bands. Somehow, trying to legitimize the whole thing only makes it worse — and usually, the CW doesn’t try. It’s way weirder to watch these two wholesome, suburban teens crawl into bed together than it is to watch the extravagant sexual exploits of the high schoolers on “Gossip Girl” or “90210.” That’s because both shows have a consistent unreal quality: set in high school, but not really true to it. Viewers sense that they can’t get away with those characters’ moral codes any more than they can their dress codes. So they don’t try.

That’s not to say teens don’t make bad calls based on hormones — of course they do. But unlike Tom and Jessie, they generally don’t abandon their families, friends and future plans to have, as Tom gleefully puts it, “sex on tap 24/7!” That advantage seems little comfort to young, real-life newlyweds making a go of it because they have a baby – people like Bristol Palin, whose triumphant re-engagement has already been marred by rumors of Levi Johnston fathering another child, and the struggling stars of the MTV reality series “Teen Mom.” Because of Palin and her peers, many teens already have an inkling of how hard taking on grownup life before you’re done growing up can be.

Which will make it interesting to see how CW’s target teen viewers react to “18 to Life.” Will they root for the couple’s us-against-the-world marriage to succeed? Will they root for Tom and Jessie to succeed — but for their marriage to fail?

Maybe they’ll just roll their eyes and decide that the only person making sense in this show is the couple’s college-student friend Carter. In episode two, the ever-irritable Tom snaps that crashing in a basement with Jessie beats living in a frat house, as Carter does. “Uh, yeah,” Carter responds in disbelief, as two giggling co-eds slip past him. “Except it doesn’t.” Which is exactly what an eighteen-year-old should say.